Typical consensus algorithm of blockchain

1. blockchain is a decentralized distributed ledger system, which can be used to register and issue digital assets, property rights certificates, points, etc., and transfer, pay and trade in a point-to-point manner. Compared with the traditional centralized ledger system, blockchain system has the advantages of complete disclosure, tamper proof, multiple payment prevention, and does not rely on any trusted third party
e to the high network delay in peer-to-peer network, the transaction order observed by each node can not be completely consistent. Therefore, the blockchain system needs to design a mechanism to reach a consensus on the sequence of transactions that occur in the same time. This algorithm to reach consensus on the order of transactions in a time window is called consensus mechanism
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2. The so-called "consensus mechanism" is to complete the verification and confirmation of the transaction in a very short time through the voting of special nodes; For a transaction, if several nodes with unrelated interests can reach a consensus, we can think that the whole network can also reach a consensus. More generally speaking, if a Chinese microblog big V, an American virtual currency player, an African student and a European tourist do not know each other, but they all agree that you are a good person, then you can basically conclude that you are not bad
as a data structure that stores data in chronological order, blockchain can support different consensus mechanisms. Consensus mechanism is an important component of blockchain technology. The goal of blockchain consensus mechanism is to make all honest nodes keep consistent blockchain view, and satisfy two properties at the same time:
1) consistency. The prefix part of the blockchain saved by all honest nodes is exactly the same
2) effectiveness. The information released by one honest node will be recorded by all other honest nodes in their own blockchain.

3. At present, there are four main types of consensus mechanisms: pow, POS, dpos, pool
1. POW workload proof, which is familiar with mining, calculates a random number that meets the rules through and or operation, that is, obtains the bookkeeping right, sends out the data that needs to be recorded in this round, and stores it together with other nodes in the whole network after verification
advantages: complete decentralization, free access of nodes
disadvantages: bitcoin has attracted most of the computing power in the world, and other blockchain applications using POW consensus mechanism are difficult to obtain the same computing power to ensure their own security; Mining causes a lot of waste of resources; The period of reaching consensus is long, which is not suitable for commercial application.

2. Proof of rights and interests of POS, a mechanism of upgrading consensus of pow; According to the token proportion and time of each node; It can rece the difficulty of mining in equal proportion, so as to speed up the speed of finding random numbers< Advantages: to a certain extent, it shortens the time to reach a consensus
disadvantages: mining is still needed, which does not solve the pain point of commercial application in essence

3. Dpos share authorization certification mechanism is similar to the voting of the board of directors, in which the coin holders cast a certain number of nodes to verify and account on their behalf
advantages: greatly rece the number of participating verification and accounting nodes, which can achieve second level consensus verification
disadvantages: the whole consensus mechanism still depends on token, and many commercial applications do not need token to exist

4. Pool verification pool, which is based on traditional distributed consistency technology and data verification mechanism; It is a consensus mechanism widely used in the instry chain at present.
advantages: it can work without token, and realizes second level consensus verification on the basis of mature distributed consistency algorithms (pasox and raft)
disadvantages: the degree of decentralization is not as good as that of bictin; The multi center business model is more suitable for multi-party participation

it has great advantages in using consensus mechanism to ensure data consistency (the consensus mechanism is first proposed by ripple, and the network transaction synchronization mechanism with data correctness priority. In the consensus network, no matter how the software code changes, if you can't reach a consensus, you can't enter the network, let alone fork)
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PS: a little black, although the consensus mechanism can absolutely ensure that there will be no hard bifurcation at any time. However, the disadvantage of this mechanism is obvious, that is, it is much longer than the current bitcoin network to reach a consensus with other nodes. In extreme cases, the consequences of disconnection in ripple consensus mechanism network are also very terrible

it is possible that one day after the power failure in your home, the whole system will no longer be able to reach a consensus with other rippled nodes (in fact, the consensus mechanism requires more than 80% of the nodes to acknowledge your data before your submission will be accepted by other nodes, otherwise it will be rejected by exclusive nodes), Even you can only empty all your 500 GB data and resynchronize to connect to other ripple nodes

so at present, the existing rippled end is not suitable for civil use (if it is commercial, the impact is relatively small. For example, RL's own rippled node is hosted in Amazon cloud data center. If it has no response for a long time, it can make high claims, and there is almost no break in that place except for large disasters). This is one of the aspects RL has always wanted to improve.

4. Chongqing jinwowo analysis distributed consensus algorithm:
the blockchain system uses the distributed consensus algorithm to generate and update data, which eliminates the possibility of illegal tampering with data from the technical level, thus replacing the third-party intermediary institutions in traditional applications to ensure trust and transaction security, and recing the time cost, human cost and resource consumption caused by maintaining credit.

5. POW: proof of work (POW), a simple explanation is a proof to confirm that you have done a certain amount of work. Because the whole process of monitoring work is usually extremely inefficient, and it is a very efficient way to prove that the corresponding workload has been completed through the certification of the work results. For example, in real life, graation certificate, driver's license and so on, are obtained by means of test results. That is to say, how much money you get depends on your effective contribution to mining. Simply understand, the better your computer performance, the more revenue you will get. This is to allocate money according to your workload. Most digital currencies, such as bitcoin, lightcoin, etc., are virtual currencies based on POW mode (the higher the computing power, the longer the mining time, the more coins you get)
pos: POS is a consensus algorithm in the public chain, which can be used as a replacement of pow algorithm. POW is a mechanism to ensure the security of bitcoin, Ethereum and many other blockchains, but POW algorithm is criticized for destroying the environment and wasting power in the process of mining. POS tries to solve these problems by replacing the concept of mining with a different mechanism
POS mechanism can be described as a kind of virtual mining. POS mainly relies on the token in the blockchain itself. In pow, a user may buy a computer for 1000 dollars, join the network to mine and proce new blocks, and get a reward. In POS, users can buy tokens of equal value with us $1000 and put them into the POS mechanism as deposit, so that users have the opportunity to generate new blocks and get rewards. In pow, if users spend $2000 on hardware equipment, they will of course get twice the computing power to mine, thus getting twice the reward. Similarly, if you invest twice as much token as the deposit in the POS mechanism, you have twice as much chance to get the right to generate new blocks.

6. How to reach a consensus on decentralized networks
in the blockchain system, there is no centralized bookkeeping institution like a bank, so it is very important to ensure the consistency of each transaction on all bookkeeping nodes, that is, to make the whole network reach a consensus. The consensus mechanism solves this problem
at present, the main consensus mechanisms are workload proof mechanism POW and equity proof mechanism POS
POW determines your chances of getting bookkeeping rights by evaluating your workload. The greater the workload, the more likely you will get this bookkeeping opportunity
POS determines your chances of getting bookkeeping rights by evaluating the number and ration of tokens you hold. This is similar to the stock dividend system, holding a relatively large number of shares can get more dividends
the principle of dpos is similar to that of POS, except that some "deputies to the National People's Congress" are selected. The main difference from POS is that the node elects several agents, which are verified and recorded by the agents
with the development of technology, more advanced consensus mechanisms may emerge in the future.

7. Jinwowo network analysis: consensus mechanism is how to reach a consensus among all accounting nodes to determine the validity of a record, which is not only a means of identification, but also a means of preventing tampering.

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